Forming press diaphragm



f March 214, 1959 Filed Jan. 4. 1954 2 sheets-Sheet 1 March 24, 1959 R.A. PAULTON l 2,878,767

FORMI'NG PRESS DIAPHRAGM Filed Jan. 4, 1954 2 Sheets-Sheet 2 1N V ENTOR.

ZO /L\ T TORNE Y6.

FORMING PRESS DIAPHRAGM Richard A. Panlton, Cozaddale, Ohio, assignor toThe Cincinnati Milling Machine Co., Cincinnati, Ohio, a corporation ofOhio Application January 4, 1954, Serial No. 402,079

3 Claims. (Cl. 113-44) This invention relates to improvements inhydraulic forming presses and has particular reference to a novel andimproved diaphragm and diaphragm mounting structure.

One of the objects of the present invention is the pro vision of animproved simplified form of diaphragm for use in connection with highpressure metal shaping or forming operations.

A further object of the invention is the provision in connection withsuch a diaphragm of improved mounting and retaining means for insuringproper retention of the diaphragm within the forming head or pressuredome of a hydraulic forming press in a manner to allow adequate yieldingof the diaphragm during a forming operation while insuring a non-leakingseal between the diaphragm structure and the forming head under highoperating pressure conditions.

A further object of the invention is the provision of improved sealingand retaining means of a simplified but efr'cient character for securingthe parts in assembled relation under non-pressure conditions.

Other objects and advantages of the present invention should be readilyapparent by reference to the following specification, considered inconjunction with the accompanying drawings forming a part thereof, andit is to be understood that any modifications may be made in the exactstructural details there shown and described, within the scope of theappended claims, without departing from or exceeding the spirit of theinvention.

Figure l is a fragmentary sectional view of a hydraulic forming pressstructure illustrating one form of the present invention.

Figure 2 is a similar View of a more simplified form thereof, and

Figure 3 is a fragmentary section of an interlock dia- -phragm retainingstructure.

The present invention is particularly adaptable for use in connectionwith present commercially known hydraulic forming presses, as forexample, the Hydro-Form machine manufactured by T he Cincinnati MillingMachine Co. Such a press includes a pair of relatively shiftableelements such as the nest plate 10, ordinarily supported by the bed ofthe machine and the movable dome element or forming head 11 having acentral cavity or recess as at 12. This recess is enclosed by an innerwall surface including side wall portions 13 extending substantiallyparallel to the central axis of the recess which blend with an upperdomed portion 14, the two together providing an open end recess forreception of uid or hydraulic pressure medium which may be introduced orexhausted from the recess or chamber 12 by way of the pipe or conduit15. In operation, this pressure may run as high as 10,000 to 15,000pounds to the square inch. In the use of such a press the work piece 16to be formed is placed on the upper face of the nest plate in overlyingrelation to the independently shiftable punch or die element 17. Whenthe elements 10 and 11 are in their closed position, the pad portion 18of the present improved diaphragm ta. Patent Vice is forced down againstthe work piece and into engagement with the member 10 in circumscribingrelation to the work piece. The parts are then locked in this position,an adequate pressure created in the chamber or recess 12, and the punch17 then moved upwardly against the Work piece. The pressure in thechamber 12, which may be 10,000 or more pounds to the square inch, isadequate in amount to hold the peripheral portion of the work piece downagainst the nest 10 as the punch is moved upwardly so that the centralportion is shaped by the diaphragm around the punch in a smooth owingmanner While the outer portion of the pad is retained in engagement withthe nest 10.

Depending on the size of the punch, and the depth of the draw, theextrusion of the punch and work piece into the recess may be entirelytaken up by material flow within the pad, or as the draw becomes deeperthere may be a tendency of the outer edge of the pad to be pulledinwardly. In previous press structures of this character it has beenconsidered necessary to mechanically lock the peripheral portion of thepad rmly to the die member 11 to retain the same in position, both whenin raised position with respect to the Work and also when in formingposition and to insure adequate seal between the pad and the die memberto prevent improper extrusion of the pad under pressure or escape of thepressure fluid from the recess.

This has resulted in a tendency toward tearing of the periphery of thediaphragm at such securing means, lessening the life of the structureand requiring the employment of complicated securing means to withstandthe pressures developed, thus involving considerable loss of time inremoval and replacement of a worn or damaged diaphragm.

The present invention and discovery relates to a dial phragm structurewhich can be satisfactorily utilized under extreme high pressureoperation conditions, which can be readily removed and replaced, whichwill provide a perfect seal against escape of the compressed operatingfluid and which will not be subject to the tearing strains andconditions existing with prior art structures.

In the present instance, the main pad portion 18 has been illustrated asformed with an upstanding rim or flange 19, the parts being of rubber orlike ilexible and compressible material. The flange 19 is preferablyinitially formed substantially of the diameter indicated of the lowerportion of the pad so that when forced upward and into interlittingengagement with the side wall portions 13 of the inner wall surface itwill be under compression, tightly interlocking with the wall 13 toprovide an airtight seal and resist withdrawal from the recess. Tofacilitate this introduction of the diaphragm the die head 11 ispreferably provided with a plate 20 having an inwardly aring recess 21tapering upwardly and into alignment with the wall 13 of the main diehead and itself closely embracing the outer periphery of the main thickor heavy pressure pad section 1S.

Intermediately of its length the rim or flange section 19 is providedwith the inwardly extending relatively rigid stitfening bead 22, thethickness of the portion of the rim or flange 19 as at 23 between thebead 22 and the pad section 18 being appreciably less than the thicknessof either the work engaging pad or that of the flange at the bead toinsure improved flexibility and potential eX- terminal shoulder portionat 24 interlocking with either the abutment or shoulder 25 formed in thedie member f 11 or alternatively with the annular abutment or shoulder26 of the limiting ring 27 which engages the upper end orI rim of saidannular ange.

If the shoulder is formed directly in the die member 1,1, as shown inFigure 2, this forms a definitely positioned stop peripherally limitingthe upward movement of the diaphragm member, either in a direct axialdirection or by tilting. If the, stop is in the form of the ring 27shown in Figure 1, it may correspondingly directly control the positionof the diaphragm at a definite point if the ring is secured to the diemember. Alternatively, and

as particularly illustrated in Figure 1, the ring may have` aslightiioatiug movement. In this instance, the diaphragm can slideupward slightly before the upper edge of the ring contacts with and islimited in its movement by engagement with the dome portion of therecess, while, alternatively, when upward pressure against the diaphragmisk released it will follow down with any downward movement of thediaphragm tending to maintain the same level.

As illustrated, there has been shown as secured to and depending-fromthe plate the annulus 28 circumscribingl the punch nest 10 when the dieelements are closed. This ring may betformed with one or more sockets29, preferably several in number containing the abutment dogs 30 lockedin position by set screws 31 and adapted to engage the lower edge of thefloating diaphragm retaining ring 32 which lies under the peripheraledge portion of the pad 18. This ring, as shown, has a close sliding fitat 33 with the inner cylindrical wall 34 of the plate 20, and has thedepending flange 35 adapted to rest upon the nest 10. When the dieelements are closed, the ring 3 2 is pressed upward, sliding on theinner wall of the plate 20, its beveled edge 36 engaging and upwardlycompressing the peripheral edge of pad 13 providing a tight seal toprevent extrusion of the edge of the pad when under pressure, but beingsupported for a yielding movement to accommodate itself to any minuterelative shiftings of the members 10 and 11 during the formingoperation. When the die elements are separated, the dogs 30 limit thedownward movement of the ring and therefore any possible downwardslippage of the diaphragm. However, when it is desired to remove andreplace the diaphragm it is merely necessary to loosen the set screws 31and retract the dogs 30 and the ringl may be readily slipped out ofposition and the diaphragm itself then withdrawn and a new one inserted.

There are three basic and different conditions under whiehthe diaphragmmust be retained and, of course, at i all times the diaphragm must sealthe pressure dome so that the entrapped oil or tiuid, under pressure orotherwise, willnot leak out. These conditions are as follows: (1)`loading-dome in raised position, no pressure in dome;v(2) dome down informing position with oil pressures exceeding 15,000 p.s.i.; and (3)dome down after forming, but oil having been exhausted to 0 pressure.This latter condition leaves diaphragm extended over finished part andpresents a very severe condition, both from stretch on the rubber andoil sealing.

T he present invention meets and satisfies the requirements of theabove-mentioned conditions. Specifically, the dome 12 in the main body11 constitutes an oil cavity, and the diaphragm structure 18-19 forms aliexible die member which will seal the oil in the dome cavity 12 underall conditions.

These two parts are the main components and function thusly. The cavityis machined or cored in the domeand the walls may be tapered orstraight, depending upon the strengthrequired in the dome. The diaphragmcan be of any rubber or rubber-like material which meets the conditionsof abrasion, stretch, and resistance to oils desired, which, of course,governs the lifeof such substance during repeated operations.

The diaphragm is inserted into the cavity in such a manner that there isenough initial tension against the sidesof -the cavity to prevent airfrom entering the cavity. This-is-veryimportant because, as previouslystated, the diaphragm is free to move,

theioilfidthe: dome to.fall out. I-Iowever.,.the.initial and*v couldfall out allowing;

pressure on the sides of the walls form an airtight chamber and as theweight of the oil and diaphragm tends to cause the diaphragm to movedown, a vacuum is formed, thereby retaining the oil and the diaphragm inthe raised position.

In the forming position, the initial pressure of the diaphragm iiangeagainst the sides of the cavity allows the pressure tobuild up on theinside of the diaphragm, forcing the diaphragm rim or tiange against thecavity walls, effectively sealing the dome during forming pressures from0 to 15,000 p.s.i.

lt may be noted that, since the diaphragm is an unclamped member, thelower portion can peel away from the sides of the cavity, allowing muchless strain on the diaphragm during severe deep draws, and at the sametime retaining the oil.

When the dome is down and the pressure has been exhausted in the domecavity, the diaphragm` can slide up into the dome cavity if the sidesare straight, thereby relieving the stretch andvstill retaining the oil.If the sides of the cavity are tapered the diaphragm can peel off at thebottom, accomplishing the same purpose. i

The above covers the basic construction of the unclamped or cup-shapeddiaphragm assembly, but for long life of the diaphragm and to easemanufacturing tolerances, some additional parts are used in theassembly.

An important part is the oating ring 32. This ring of solid materialspans the gap between the Sides of the dome cavity and the nest plate.Unless this gap was held to a few thousandths of an inch, during formingunder high pressures, the diaphragm would extrude, shortening the lifeof the diaphragm.

In order to assure the diaphragm being level at all times, especiallyduring the time that the domeis coming down on the blank, retaining ring27 is used. It can eitherbe bolted to the inside of the dome cavity orcan lay loose on top of the diaphragm as shown in the drawing.

When coming down on a preformed part on a deep drawn part, if notrestrained in some manner, the diaphragm might turn inside out. Toprevent action of this sort inthe form of the invention shown in Figure2, there has been provided the stilening bead 22 and intermediatethinner iiexible portion 23 of the rim of the diaphragm. This stilfeningbead serves to hold the upper portion of the diaphragm rim tightlyagainst the inner wall of the dome to prevent such action. In the eventof possibility of more extreme strains on therdiaphragm, use may be madeof the supplemental` restrain.- ing ring 37 as illustrated in Figure lwhich is loosely and removably mounted within the diaphragmintermediateV the'rib 22. and the pad 18, the spacing relationshipbetween the exterior of the ring and the inner face of the rim or flangeon the diaphragm as well as the spacing relation between the rib 22 andpad 1S with respect to the width or height of the floating ring 37 beingsuch as to permit of a certain amount of yielding and stretching of theintermediate thinner portion 23 so that the diaphragm, as an entirety,may properly accommodate itself to the stretching and displacementseffected as by the punch 17 while itse general movement is limited bythe interengagement of the bead 22 with the restraining ring, so thatpossibility of disengagement of the upper portion of the retainingflange with respect to the inner wall of the dome, even under mostextreme conditions, is prevented.

In Figure 3 the upper abutment ring 27 has been illustrated as securedto the wall of the dome by the fastenings 38. This ring, as indicated inboth Figures 1 and 3, has the downwardly extending inner tiange portion39 spaced from the wall of the dome to provide a peripheral recessreceiving the upper edge or shoulder portion 24 of the rim of thediaphragm. In Figure 3, the depending flange 39 is formed with theoutwardly extending double tapered header rib t0-projecting toward butin spaced;

relation to the wall 13 of the dome and adapted to t into the groove 41in the flange of the pad. In assembling the inwardly extendingcompressible rib 42 on the diaphragm it is forced upward past the rib 40which provides a narrow entrance throat for the recess 43. As it isforced up into the dome, rib 42 will spring into and extend within therecess 43 between the ange 39 and shoulder 26 on the rim and annularwall 13. This may be readily effected by partially inserting the flangeof the diaphragm into the dome recess and then closing together the dieelement 11 and the nest plate 10 providing the necessary force to movethe parts into assembled relation shown in Figure 3. This structure hasthe additional advantage over those previously described of providing amechanical interlock between the retaining ring and the diaphragm whichwill permit a certain amount of free or unrestricted relative movementof the diaphragm and the dome while the interengagement of the partswill aid in mechanically holding the diaphragm in position when the domeis raised to prevent separation or relative tilting of the parts. Forremoval, the dome is preferably slightly raised and sucient pressurebuilt up in the enclosed dome area to aid in snapping the diaphragm outof the dome. It will be understood that relatively low air pressure willbe adequate for this purpose, avoiding the possible loss of the oil orhydraulic medium normally employed for forming pressure creatingpurposes.

It will be ovious that the double tapered form of the bead or ange 40facilitates initial positioning of the diaphragm prior to the snap ofits bead 42 into the recess 43.

What is claimed is:

1. A die element for a cyclically operable forming press comprising ahollow pressure dome having an inner wall surface enclosing an open endrecess in the dome for receiving liquid under pressure, said wallsurface including side wall portions extending substantially parallel tothe longitudinal axis of the recess, a flexible closure for the open endof said recess mounted for bodily sliding movement therein during thepress cycle when pressure is removed from the liquid, said closureincluding a thick resilient pad portion of substantially uniformthickness peripherally interiitting with said side wall portions of theinner wall surface to close the recess against the escape of liquidtherefrom and having an upstanding annular ange extending normal to saidpad portion adapted for intertting sliding engagement with said sidewall portions, the length of said ilange being less than that of saidside wall portions so as to permit sliding movement of the closurewithin the recess during a press cycle to prevent the inner end of theange from separating from the side wall portions of the recess andbreaking the liquid seal when pressure is removed from the liquid in therecess and a formed or preformed part is projecting up into the recess,and means in said recess lying in a plane perpendicular to thelongitudinal axis of said recess for engaging the inner end of said angeto limit sliding movement of the closure into the recess to the continesof the parallel side wall portions of the recess and also to preventcocking of the closure within the recess.

2. The die element of claim 1 including sealing means for preventingextrusion of said closure around the peripheral edge of said padportion, said means comprising a oating ring located inthe mouth of saidrecess beneath said closure and extending around the periphery thereof,said ring having a peripheral face thereon which is adapted forinterltting sliding engagement with said side wall portions of the innerwall surface to provide support for said ring in the mouth of saidrecess, and an annular face thereon inclined with respect to saidperipheral face which is adapted to engage the face of said pad portionaround the peripheral edge thereof and seal the same against extrusionfrom the recess.

3. The die element of claim 2 including a nest mov-able with respect tosaid dome for closing the open end of the recess therein, and anabutment surface on said ring for contacting a mating surface on saidnest to hold the ring within the recess when pressure is applied to saiddome.

References Cited in the le of this patent UNITED STATES PATENTS2,204,648 Baker June 18, 1940 2,385,083 Kemerer Sept. 18, 1945 2,550,672Chyba May 1, 1951 2,771,850 Wheelon Nov. 27, 1956 2,783,727 Hoffman Mar.5, 1957

